Contents
- How to use this guide
- Where it fits
- Scale vs corrosion: the simple model
- Key drivers & what to measure
- Program building blocks (what a “good program” includes)
- Monitoring signals (quick KPIs)
- Troubleshooting: symptom → first checks
- Specification & acceptance checks (COA/SDS)
- RFQ notes (what to include)
How to use this guide
This guide helps B2B teams align procurement, EHS, and operations on selection criteria, acceptance checks, and monitoring signals. It’s written to be practical across cooling towers, boilers, and closed-loop systems.
Safety note: Many water treatment products are corrosive (acids/alkalis), oxidizing (some biocides), or otherwise hazardous. Always follow site procedures and the supplier SDS/labels.
Where it fits
- Process goal: define the KPI you are optimizing (uptime, heat transfer efficiency, asset life, compliance, or cost).
- Operating window: temperature, pH, conductivity/cycles, flow, pressure, residence/contact time.
- Interfaces: metallurgy, elastomers, coatings, and (if applicable) membranes.
- Constraints: discharge limits, site EHS rules, restricted substances, storage limitations.
Scale vs corrosion: the simple model
| Problem | What it is | What you see | Why it hurts |
|---|---|---|---|
| Scale | Mineral deposits that precipitate when conditions favor solids formation | Reduced heat transfer, rising ΔP, visible deposits on surfaces | Higher energy cost, reduced capacity, forced shutdowns |
| Corrosion | Metal loss driven by electrochemical reactions (often accelerated by oxygen, low pH, salts, deposits) | Leaks, thinning, rust, pitting, elevated iron/copper in water | Asset failure risk, unplanned downtime, safety and environmental impact |
Trade-off to remember: Some conditions that reduce scaling can increase corrosion (and vice versa).
A “good program” is usually a balance: control cycles and chemistry, then use targeted inhibitors + monitoring.
Key drivers & what to measure
| Driver | Scale impact | Corrosion impact | What to measure / trend |
|---|---|---|---|
| Temperature | Often increases precipitation risk on hot surfaces | Can accelerate reaction rates | Process temperature, approach temperature, exchanger ΔT |
| pH / alkalinity | Drives carbonate scaling tendency | Low pH can accelerate corrosion; high pH can help passivate some metals (system-dependent) | pH, alkalinity, control stability (probe calibration) |
| Salts / conductivity / cycles | Higher concentration increases scaling tendency | Higher chlorides and conductivity can increase corrosion risk | Conductivity, cycles of concentration, chloride, blowdown rate |
| Oxygen / oxidants | Indirect | Often increases corrosion risk (especially with poor control) | Dissolved oxygen (where measured), ORP/oxidant residual, deaeration performance |
| Deposits / biofilm | Can seed/hold scale and concentrate ions at surface | Can cause under-deposit corrosion and pitting | Visual inspection, ΔP trends, microbiology checks, cleanliness factor (as used) |
Program building blocks
A reliable scale/corrosion program typically combines these elements:
- Control the basics: stable pH, controlled cycles/conductivity, reliable blowdown, accurate dosing.
- Choose the right chemistry: scale inhibitor/antiscalant, corrosion inhibitor, dispersant; biocide strategy where biofouling is a driver.
- Define monitoring points: where you sample and how often (consistency beats “perfect” methods).
- Verify with evidence: coupons/probes (for corrosion), inspection findings (for scale), and trend charts (for both).
Monitoring signals (quick KPIs)
| Goal | High-value signals | What “bad drift” looks like |
|---|---|---|
| Scale control | Approach temperature, exchanger ΔT, differential pressure, conductivity/cycles trend | Rising approach/ΔT at same load; steadily rising ΔP; cycles uncontrolled |
| Corrosion control | Corrosion coupons/probes, pH, conductivity, metal ions (system-dependent) | Coupon rate trending up; sudden pH drops; conductivity spikes; localized failures |
| Biofouling contribution | ORP/oxidant residual (where used), slime observations, microbial counts, ΔP | Residual collapses quickly; slime/odor; ΔP increases despite stable solids |
Troubleshooting: symptom → first checks
| Symptom | First checks | Likely direction |
|---|---|---|
| Scale appears / heat transfer drops | Confirm load and instrumentation; check cycles/conductivity control; verify inhibitor dosing calibration; review feedwater changes (hardness/alkalinity/silica) | Dosing/control drift or chemistry mismatch to current water |
| Rising differential pressure | Check filtration/strainers; confirm solids loading; inspect for deposits/biofilm; verify dispersant/biocide strategy | Deposit/biofouling issue or solids management gap |
| Pitting / leaks / localized corrosion | Confirm metallurgy & locations; check oxygen ingress; review chloride/conductivity; inspect for under-deposit corrosion; verify inhibitor compatibility | Local driver (oxygen/deposits/chlorides) + insufficient protection |
| Corrosion rate increases (coupons/probe) | Validate coupon method/time; check pH swings and oxidant interactions; confirm product consistency (COA); verify dosing equipment | Process drift or inconsistent product/dosing |
Specification & acceptance checks (COA/SDS)
When comparing products, ask for data you can verify on receipt:
| Category | What to request | What to verify on receipt |
|---|---|---|
| Identity | Product name/grade, manufacturer, batch/lot traceability | Labels match PO; batch recorded; packaging intact |
| Quality (COA core) | Assay/active content, density, appearance; pH (if relevant); viscosity (if relevant) | Meets agreed limits; no phase separation; consistent for dosing |
| Safety | Up-to-date SDS, handling precautions, required PPE, transport classification | EHS approval; storage segregation requirements satisfied |
| Packaging | Drum/IBC/bulk; liner type; closures; labeling | Compatible with pumps/hoses; secondary containment capacity |
| Logistics | Lead time, Incoterms, shelf life, storage requirements | Shelf life acceptable; FEFO practicable; storage conditions available |
RFQ notes (what to include)
- System type (cooling tower, boiler, closed loop) and key operating conditions (temperature, pH, flow, cycles, pressure).
- Feedwater or makeup analysis (hardness, alkalinity, silica, chlorides, conductivity; add iron/manganese if relevant).
- Materials of construction (metals, elastomers, coatings; membrane type if applicable).
- Target KPI and acceptance criteria (ΔT/approach, ΔP, coupon targets, inspection criteria).
- Monitoring points and sampling frequency (who measures what, where).
- Estimated monthly volume, packaging preference, delivery country and compliance requirements.
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Educational content only. Always follow site EHS rules and the supplier SDS for safe use.